According to researchers at the University of Bristol in the U.K., participants who consumed alcohol from a straight-sided glass drank less than those who were served alcoholic beverages in glasses with curved sides. Social drinkers, both male and female, attended two sessions. They were randomly assigned to drink either beer or a soft drink from either a curved or a straight-sided glass. Next, they completed a task that asked them to identify what they thought was the midpoint of each type of glass.
Participants were significantly slower to consume an alcoholic beverage in a straight glass compared with one served in a curved glass. (Researchers quantified the difference as 60% slower.) This effect was observed only for a full glass and not a half-full one, and was not observed for a non-alcoholic beverage.
When it came time to judge the halfway point of a glass, participants misjudged the midpoint of a curved glass to a greater degree than that of a straight glass, and—perhaps unsurprisingly—the more time they spent drinking, the greater the degree of error.
The study, “Glass Shape Influences Consumption Rate for Alcoholic Beverages,” was published by the Public Library of Science.